Although the present invention is discussed herein, particularly as it relates to down jarring activities in connection with coil tubing, it should be born in mind that this jarring mechanism is also capable of efficient use in connection with conventional jointed tubing for jarring activities. Further, the telescoping components of this down jar mechanism may be provided with splined interconnection so as to be efficiently used for snubbing or drilling activities and it may be used to release locking mandrels, broaching tools shear pins etc. It may also be employed in combination with an up jarring mechanism or with an accelerator to enhance jarring activities. This jarring mechanism may also be employed for fishing activities, wherein objects that are stuck within the well bore (fish) are released by jarring activities so that they can be removed from the well.
Coil tubing fishing is becoming very popular with the oil industry due to the speed of getting the tubing into and out of the well bore, plus its ability to pull and circulate with high pressure, such as for cleaning the top of a fish to facilitate a fishing operation. It is desirable, therefore, to provide a mechanical down jarring mechanism that is capable of functioning to achieve jarring activities that re especially suitable for coil tubing to overcome the friction forces that often cause sticking of tubing that is being run into a well. It is also desirable to provide a jarring mechanism that functions efficiently during horizontal drilling activities to release stuck drill pipe and to provide downhole forces for movement of pipe in the horizontal portion of a well bore such as during operation of a mud motor for drilling. This invention is also effective for work-over activities for petroleum wells to position well service tools, release downhole tools and to provide other servicing functions.
It is well known that fishing activities are exceedingly difficult where coil tubing is involved. In approximately 50% of the cases, it is impossible where coil tubing is being employed to release the fishing tools due to the inability to develop a downwardly directed jarring or shock load on the fishing tool to release it from the fish. Coil tubing units are hydraulically controlled and cannot move downward with adequate motion to generate a shock load to fishing tools. All fishing tools, after having been jarred on for some time with upwardly directed jarring force, require downward shock impact for releasing. Jarring down is also necessary to free the fish from the fishing tool. Thus a recockable down jar mechanism is essential to effective well servicing operations.
The inventor of the subject matter hereof is considered the leader or pioneer in the industry to introduce vertical release and catch, on/off fishing tools for the purpose of coil tubing fishing. These technological advancements in fishing tools and fishing technology are considered especially important because coil tubing can not be rotated for the reason that it will twist off. In order to complete the technology to accomplish downward fishing operations with coil tubing, it becomes very necessary to develop a down jar to complete the fishing string in order to release fishing tools should the operator be unable to retrieve the fish.
Until now, the operator of the fishing equipment, in order to disengage coil tubing from fishing tools, will pump a steel ball down the coil tubing to actuate a tool release mechanism. After this has been done, the operator will then install wireline fishing equipment and enter the well with spang or tubular jars to release the fishing tool. These necessary activities become a great hindrance to the commercial success of fishing operations because of the time and expense that is involved.
Mechanical recockable down jar mechanisms have been developed, the latest of such being presented in Applicant's co-pending application identified above. Though down jars having mechanical recocking mechanisms are being utilized, it is considered desirable to provide a down jar mechanism that is designed for hydraulic recocking to facilitate sequential recocking and firing of the down jar mechanism even when a fish or other downhole object is not coupled to it. In the alternative the down jar mechanism may provide for both hydraulic and mechanical recocking, thus providing a degree of operational redundancy for commercial effectiveness.